The present invention relates to a system, including methods and devices, utilizing wireless sensor devices and RFID (radio-frequency identification) transponders. Specifically, the present invention relates to a system incorporating novel devices and methods that enable point-of-use and on-demand commissioning of RFID transponder-equipped wireless sensors.
Radio-frequency identification (RFID) transponders enable improved identification and tracking of objects by encoding data electronically in a compact tag or label. And, advantageously, the compact tag or label does not need external, optically recognizable or human-readable markings. In fact, using the Gen2 EPC specification, a three-meter read-distance for RFID transponders is common—even on high-speed material handling lines.
Radio-frequency identification (RFID) transponders, typically thin transceivers that include an integrated circuit chip having radio frequency circuits, control logic, memory and an antenna structure mounted on a supporting substrate, enable vast amounts of information to be encoded and stored and have unique identification. Commissioning, the process of encoding specific information (for example, data representing an object identifier, the date-code, batch, customer name, origin, destination, quantity, and items) associated with an object (for example, a shipping container), associates a specific object with a unique RFID transponder. The commissioned transponder responds to coded RF signals and, therefore, readily can be interrogated by external devices to reveal the data associated with the transponder.
Current classes of RFID transponders rank into two primary categories: active RFID transponders and passive RFID transponders. Active RFID transponders include an integrated power source capable of self-generating signals, which may be used by other, remote reading devices to interpret the data associated with the transponder. Active transponders include batteries and, historically, are considered considerably more expensive than passive RFID transponders. Passive RFID transponders backscatter incident RF energy to specially designed remote devices such as interrogators.
Combining the benefits of the latest technology in RFID transponders with sensing devices, a broader class of devices called wireless sensors is emerging. Wireless sensors have a unique identity, sense one or more attributes within its environment, and report its identity and data corresponding to the sensed attributes. For example, a wireless sensor interprets environmental conditions such as temperature, moisture, sunlight, seismic activity, biological, chemical or nuclear materials, specific molecules, shock, vibration, location, or other environmental parameters. Wireless sensors are distributed nodes of computing networks that are interconnected by wired and wireless interfaces.
Wireless sensors, made using silicon circuits, polymer circuits, optical modulation indicia, an encoded quartz crystal diode, or Surface Acoustic Wave (SAW) materials to affect radio frequency or other signaling methods, communicate wirelessly to other devices. For example, certain embodiments of wireless sensors communicate on a peer-to-peer basis to an interrogator or a mobile computer. Communication methods include narrow band, wide band, ultra wide band, or other means of radio or signal propagation methods.
Generating a unique serial number is imperative, and is required for EPCglobal RFID tagging implementations. Serialization requires a central issuing authority of numbers for manufacturers, products, and items to guarantee uniqueness and to avoid duplication of numbers. Blocks of numbers are distributed to remote locations globally. Unless a product (or SKU) is serialized at one location, the numbering space is usually partitioned according to some method, or each remote location receives each number one-by-one. Either way, there is eventually a reconciliation of serial number usage with a granularity of either one or several numbers at a time.
A preferred method of generating unique serial numbers is to assign unique numbers in a central location, such as in a label converter facility where unique bar coded labels are printed. Each unique label is then packed and shipped to remote locations, usually either in sheets or rolls. Upon arrival at a manufacturing facility, rolls are loaded onto high speed label applicators that apply one serialized label onto each carton. As those serialized cartons move through the supply chain, they may eventually arrive at a case pick location, a receiving dock, or similar location where a serialized carton is selected for having an RFID transponder applied to it. Using a bar code scanner to read one or more bar codes sufficient information can be collected to uniquely encode that data into an RFID transponder and apply it to that carton.
The uniqueness of an identifier is critical to the success of almost any tracking system. Assuring uniqueness is not necessarily simple. A generically descriptive bar code can be matched to authorizations for selected numbering systems that provide additional data fields including a unique serial number or using algorithms that assure uniqueness through numerical representations of time and space.
Certain prior art systems use printer encoders to merge the printing and RFID transponder encoding operations into a single atomic transaction. This method is more expensive in every respect. It requires mobile distributed printing with nearly perfect networking implementations in order to achieve a smooth, easy, and regular manual transponder application process. This all comes at a higher price, size, and weight. Prior art implementations tend not to be mobile, as represented by U.S. Pat. No. 7,066,667 issued to Chapman et al. on 27 Jun. 2006 and include U.S. Pat. No. 5,899,476 issued to Barrus et al. on 31 May 2005, or by U.S. Pat. No. 6,246,326 issued to Wiklof et al. on 12 Jun. 2001, describe a device that commissions an RFID transponder with a printed label. This approach, however, introduces unnecessary waste, cost, and propensities for error. There is a growing category of applications that do not require anything other than a custom-encoded RFID transponder. This prior art calls for the inclusion of label printer hardware and related consumable materials that are not necessary for many RFID applications. Unneeded printer mechanisms create unnecessary complexities, size, and weight. In some instances this additional bulk hinders practical mobile applications. The result is that tagging solutions that include printing result in a higher total cost of ownership than a pure RF tag encoding system.
So, despite recent advances in RFID technology, the state-of-the-art does not fully address the needs of simple, efficient, economical, high-volume, reliable deployment and commissioning of RFID transponders and wireless sensors. Large-scale adoption of RFID transponders depends on systems utilizing reliable, low-cost transponders deployed at thousands of distributed locations that implement simple and efficient manual transponder commissioning means. Such systems should further include processes for efficient commissioning of batches of RFID transponders, without the need for realtime wireless connectivity.